A U.S. Court of Appeals’ decision to vacate EPA’s rule to reduce hydrofluorocarbons (HFCs) could cost at least 3.6 billion metric tons of avoided emissions through 2050 and limits U.S. options to fully implement the Kigali Amendment to the Montreal Protocol, which would reduce cumulative U.S. emissions by 9.5 billion metric tons. This research note report analyzes potential impacts of the court decision, as well as potential alternatives for the U.S. to fully implement the Kigali Amendment.